We deal with surface turbulent flux calculations on a tropical glacier and analyse the related errors. We use data from two eddy-covariance systems and wind speed and temperature profiles collected during a 2-month measurement campaign undertaken within the atmospheric surface layer of the glacier. We show the largest error sources are related to roughness length uncertainties and to nonstationarity of the flow induced by the interaction of outer-layer eddies with the surface-layer flow.

This study presents a new instrument called a low-cost albedometer (LCA) composed of two illuminance sensors. The ratio between reflected vs. incident illuminances is called the albedo index and can be compared with actual albedo values. We demonstrate that our system performs well and thus provides relevant opportunities to document spatiotemporal changes in the surface albedo from direct observations at the scale of an entire catchment at a low cost.

As snowcover becomes patchy during snowmelt, energy is advected from warm snow-free surfaces to cold snowcovered surfaces. This manuscript proposes a simple sensible and latent heat advection model for snowmelt situations that can be coupled to one-dimensional energy balance snowmelt models. The model demonstrates that sensible and latent heat advection fluxes can compensate for one another, especially in early melt periods.

About 150 of the 250 000 inventoried glaciers are currently monitored with surface mass balance (SMB) measurements. To increase this number, we propose a method to retrieve annual and summer SMB from optical satellite imagery, with an application over 30 glaciers in the French Alps. Computing the glacier-wide averaged albedo allows us to reconstruct annual and summer SMB of most of the studied glaciers, highlighting the potential of this method to retrieve SMB of unmonitored glaciers.

In this paper we present a case study from a heterogeneous pasture site in the Canadian prairies, where we have quantified the various components of the water balance on the field scale, and critically examine some of the simplifying assumptions which are often invoked when applying water budget approaches in applied hydrology. We highlight challenges caused by lateral fluxes of blowing snow and ambiguous partitioning of snow melt water into runoff and infiltration.

We evaluated distributed and semi-distributed modeling approaches to simulating the spatial and temporal evolution of snow and ice over an extended mountain catchment, using the Crocus snowpack model. The distributed approach simulated the snowpack dynamics on a 250-m grid, enabling inclusion of terrain shadowing effects. The semi-distributed approach simulated the snowpack dynamics for discrete topographic classes characterized by elevation range, aspect, and slope.

This study demonstrates a robust procedure for accumulating precipitation gauge measurements and provides an analysis of bias corrections of precipitation measurements across experimental sites in different ecoclimatic regions of western Canada. It highlights the need for and importance of precipitation bias corrections at both research sites and operational networks for water balance assessment and the validation of global/regional climate–hydrology models.

Studies performed in the outer tropics suggested that Positive Degree-Day (PDD) model should be used with caution in tropical areas because temperature is not directly linked to the main local melting processes. Using an enhanced PDD model in the inner tropics during nine years allowed an accurate modelling of the glacier-wide mass balances and ablation on the Antizana glacier. This proves the high sensitivity of glaciers to temperature changes in Ecuador.

Remote sensing techniques can provide useful large-scale estimates of soil moisture. However, these methods often only sense near-surface soil moisture, whereas many applications require estimates of the entire root zone. In this study we propose and test methods to "depth-scale" the shallow soil moisture measurements obtained using the cosmic-ray neutron probe to represent the entire root zone, thereby improving the applicability of this measurement approach.

Three different types of gridded precipitation products are compared in a high glaciated tropical mountain environment (Cordillera Blanca, Peru): ground-based interpolation, a satellite-derived product (TRMM3B42), and outputs from the WRF regional climate model. While none of the products meets the challenge of representing both accumulated quantities and frequency of occurrence at the short timescale, we concluded that new methods should be used to merge those various precipitation products.

We deal with surface turbulent flux calculations on a tropical glacier and analyse the related errors. We use data from two eddy-covariance systems and wind speed and temperature profiles collected during a 2-month measurement campaign undertaken within the atmospheric surface layer of the glacier. We show the largest error sources are related to roughness length uncertainties and to nonstationarity of the flow induced by the interaction of outer-layer eddies with the surface-layer flow.

We evaluate the potential of Pléiades sub-meter satellite stereo imagery to derive digital elevation models (DEMs) of glaciers and their elevation changes. The vertical precision of the DEMs is ±1 m, even ±0.5m on the flat glacier tongues. Similar precision levels are obtained in accumulation areas. Comparison of a Pléiades DEM with a SPOT5 DEM reveals the strongly negative region-wide mass balances of glaciers in the Mont Blanc area (-1.04±0.23m at 1 water equivalent) during 2003-2012.

We present a new surface melt scheme for land ice. Derived from the energy balance of melting surfaces, the scheme may be particularly suitable for long ice-sheet simulations of past and future climates. It is computationally inexpensive and can be adapted to changes in the Earth's orbit and atmospheric composition. The scheme yields a better spatial representation of surface melt than common empirical schemes, when applied to the Greenland Ice Sheet under present-day climate conditions.

We apply a framework to compare and objectively accept or reject competing melt and run-off process models. We found no acceptable models. Furthermore, increasing model complexity does not guarantee better predictions. The results highlight model selection uncertainty and the need for rigorous frameworks to identify deficiencies in competing models. The application of this approach in the future will help to better quantify model prediction uncertainty and develop improved process models.

The balance of longwave and shortwave radiation plays a central role in the summer melt of Arctic sea ice. It is governed by clouds and surface albedo. The basic question is what causes more melting, sunny skies or cloudy skies. It depends on the albedo of the ice surface. For snow-covered or bare ice, sunny skies always result in less radiative heat input. In contrast, the open ocean always has, and melt ponds usually have, more radiative input under sunny skies than cloudy skies.

Knowledge of the snow reservoir is important for energy production and water resource management. In this study, a detailed snow model is run over southern Norway with two different sets of forcing data. The results show that forcing data consisting of post-processed data from a numerical weather model (observations assimilated into the raw weather predictions) are most promising for snow simulations when larger regions are evaluated.

We show through observations and simulations that cold content, a key part of the snowpack energy budget, develops primarily through new snowfall. We also note that cold content damps snowmelt rate and timing at sub-seasonal timescales, while seasonal melt onset is controlled by the timing of peak cold content and total spring precipitation. This work has implications for how cold content is represented in snow models and improves our understanding of its effect on snowmelt processes.

Idealized model experiments demonstrate that, in addition to a gradual climate change, changing daily to weekly variability of meteorological variables and extreme events will also have an impact on mean annual ground temperature in high-latitude permafrost areas. In fact, results of the land surface model experiments show that the projected increase of variability of meteorological variables leads to cooler permafrost soil in contrast to an otherwise soil warming in response to climate change.

Shifts in hydrologic conditions will be a key factor for the sustainability of Arctic ecosystems under future climate change. Using a long-term manipulation experiment, we analyzed how energy exchange processes within a permafrost ecosystem react to sustained dry conditions. Changes in several important ecosystem characteristics lead to reduced evapotranspiration and increased sensible heat fluxes. Heat transfer into the soil was strongly reduced, keeping the permafrost colder.

Our overall goal is to improve the numerical modeling of glacier melt in order to better predict the future of glaciers in Western Canada and worldwide.
Most commonly used models rely on simplifications of processes that dictate melting at a glacier surface, in particular turbulent processes of heat exchange. We compared modeled against directly measured turbulent heat fluxes at a valley glacier in British Columbia, Canada, and found that more improvements are needed in all the tested models.

Biological growth darkens snow and ice, causing it to melt faster. This is often referred to as bioalbedo. Quantifying bioalbedo has not been achieved because of difficulties in isolating the biological contribution from the optical properties of ice and snow, and from inorganic impurities in field studies. In this paper, we provide a physical model that enables bioalbedo to be quantified from first principles and we use it to guide future field studies.

The regional climate model HIRHAM5 is evaluated over Vatnajökull, Iceland, using automatic weather stations and mass balance observations from 1995 to 2014. From this we asses whether the model can be used to reconstruct the mass balance of the glacier. We find that the simulated energy balance is underestimated overall, but it has been improved by using a new albedo scheme. The specific mass balance is reconstructed back to 1980, thus expanding on the observational records of the mass balance.

We present the snowpack model SEMIC. It calculates snow height, surface temperature, surface albedo, and the surface mass balance of snow- and ice-covered surfaces while using meteorological data as input. In this paper we describe how SEMIC works and how well it compares with snowpack data of a more sophisticated regional climate model applied to the Greenland ice sheet. Because of its simplicity and efficiency, SEMIC can be used as a coupling interface between atmospheric and ice sheet models.

We present 7 years of field work and modelling to assess the importance of the loss of water from the snow by means of evaposublimation in the Mediterranean mountains of Sierra Nevada. The actual evaposublimation rates were detected through detailed measurement of the mass fluxes from the snow. These data have led to some improvements in the modelling of the snow dynamics in this kind of mountainous semiarid regions. Evaposublimation is estimated to range 24–33% of total annual snowfall.

Atmospheric–glacier surface interactions govern melt, where each variable has a different impact depending on the region and time of year. To understand these impacts and their year-to-year variability on summer melt extent, we examine melt sensitivity to different meteorological variables at a glacier in the Canadian Rockies. Cloud conditions, surface albedo, temperature, and humidity are all important to melt extent and should be considered in models of glacier response to climate change.

Despite the crucial role of polar regions in the global climate system, the limited availability of observations on the ground hampers a detailed understanding of their energy budget. Here we develop a method to use satellites to fill these observational gaps. We show that by sampling satellite observations in a smart way, coverage is greatly enhanced. We conclude that this method might help improve our understanding of the polar energy budget, and ultimately its effects on the global climate.

We identify and correct station-tilt-induced biases in insolation observed by automatic weather stations on the Greenland Ice Sheet. Without tilt correction, only 40 % of clear days have the correct solar noon time (&pm;0.5 h). The largest hourly bias exceeds 20 %. We estimate the tilt angles based on solar geometric relationship between insolation observed on horizontal surfaces and that on tilted surfaces, and produce shortwave radiation and albedo that agree better with independent data sets.

Clouds are shown to force fundamental changes in the surface energy and mass balance of Brewster Glacier, New Zealand. Cloudy periods exhibit greater melt due to increased incoming long-wave radiation and higher atmospheric vapour pressure rather than through minimal changes in mean air temperature and wind speed. Surface mass-balance sensitivity to air temperature is enhanced in overcast compared to clear-sky periods due to more frequent melt and a strong precipitation phase to albedo feedback.

Our work quantifies the effect of snow/ice cover on Earth's top-of-atmosphere solar energy budget. We used higher resolution MODIS data, combined with microwave retrievals of snow presence and radiative kernels produced from 4 different models for Cryosphere Radiative Effect (CrRE) estimation. We have estimated a global land-based CrRE of about -2.6Wm-2 during 2001-2013, with about 59% of the effect originating from Antarctica. We were also be able to resolve contribution from mountain glaciers.

This paper presents point-scale surface energy balance on Chhota Shigri Glacier, Western Himalaya, India. Energy is available for melting only in summer-monsoon. Net all-wave radiation is the main heat flux towards the glacier surface accounting for 80% of the total melting energy followed by sensible (13%), latent (5%) turbulent and conductive (2%) heat fluxes. The intensity of summer-monsoon snowfalls is found among the most important drivers controlling the mass balance of this glacier.

Favier, V., Wagnon, P., and Ribstein, P.: Glaciers of the outer and inner tropics: A different behaviour but a common response to climatic forcing, Geophys. Res. Lett., 31, L16403, https://doi.org/10.1029/2004GL020654, 2004.

Climate variations might change the frequency of typical weather conditions. We present a weather pattern classification as an useful tool for identifying changing glacier wind regimes. We show the intensity of turbulent heat exchanges between ice and air changes with these regimes, as well as the importance of discrepancies between bulk-aerodynamic and eddy-covariance fluxes. The results suggest these discrepancies influence melt estimates from surface energy balance calculations.